Biotin intermediate



Patented Jan. 25, 1949 2,460,225

'UNITED STATES PATENT OFFICE BIOTIN INTERMEDIATE Stanton A. Harris, Westfield, and Karl Folkers, Plainfield, N. J., assignors to Merck & (30., Inc., Itahway, N. J a corporation of New Jersey No Drawing. Application December 15, 1945, I

Serial No. 635,427 1 13 Claims. (Cl. 260-329) 1 2 This invention is concerned generally with novel chemical compounds and processes of pre- RC RC0 paring the same; more particularly it relates to NH NH NE NH l l novel compounds useful as intermediates in synon -cn 011* thesis of the growth-promoting factor, biotin. 5 l e l C G This is a continuation-in-part of co-pending GIL-s C CE(OH)3GO2R- CHFS C application Serial No. 554,453, filed September I (90) (9b) 16, 1944. 4

Biotin is known to be one of the isomers of 2 Hydrogen the chemical compound 2-(4-carboxy-butyl)- 10 lcatalyst 3:4-ureido-tetrahydrothiophene, having the empirical formula C10H16O3N2S, and the structural R(\30 Boo formula: 0 f f f l 16 2 s CH COR 10 H? (3H 0 2CH( 2); 2 v( H2O--S-CHCHgOHzCHzCHzC 01H lore, then 11+ It is now found that this compound can be NH NH synthesized by reactions indicated as follows: 20 y l 2 CH-GH NE, NH, 1

1 I CHi-S-CE (C112) 40 0211 (11 ore-coir! OH-GOaH I XCH5C09H l CHr-SH CHr-SCH2C 01H l 0 OX:

l Hie-(Lain I 300x 1 cH-0n RCO R00 l t I I CH S-CH(OHz)iOOzl-1 12) NH NH 7 i n; COR ROE (:11 C011 1 a l 2 In the above formulae, It represents an alkyl, CHTSCH2COE aryl or arylalkyl group; X, a halogen, M an: (4) (3) alkali metal or an alkaline earth metal; and

Y--N= is a radical selected from the group lROM which consists of cximino, arylhydrazino andsemicarbazido radicals. The reactions above in-'- 300 R00 dicated are conducted as follows: 2-amino-3- l l 40 mercapto propanoic acid (1) and chloroethanoic NH 0 NH 0 I l \l 11 acid are condensed in an alkaline aqueous solu- 5 E tion to form 2-amino-3-carboxymethyl-mer- CH -S-CCOQR OHi-S-CHz capto-propanoic acid (2); which is then treated (6) with an acylating agent, such as an acyl halide,. in an aqueous alkaline solution to yield 3-acyl-" (5) o=omcm go l -amido-3-carboxymethylmercapto-propanoic .acid' (3-). This product is esterified using a mineral RC0 RC0 acid catalyst to produce the diester (4) of the NH N Y g 0 acid (3), and the diester is treated with alkali PM;2 a u metal alcoholate or an alkaline earth metal al-- coholate to yield the 2-a1kali metal or the 3-: CHPS Q;QH(QH,)3C0,R GH -S -C=CH(CH CO,R alkaline earth metal derivative of an ester of (8) (7) 2-carboxy-B-keto-Q-acylamido tetrahydrothio'. phone (5). This compound, when heated with.

(R00) 0 a dilute mineral acid, is hydrolyzed and decar (H) boxylated to produce B-keto-4-acylamido-tetra-' hydrothiophene (6) which, when reacted with 4-carboxybutanal ester in a lower aliphatic alcohol reaction medium containing iperidine and a lower aliphatic carboxylic acid, produces an ester of 2-(4-carboxy-butylidene)-3-l eto-4- acylamido tetrahydrothiophene (7) This prodnot, when reacted'with a compound selected from the group which consists of hydroxylamine, arylhydrazines and semicarbazide yields an ester of the corresponding 3-ketosubstitution-productof 2 (4'-carboxybuty1idenc)-3-keto-4-acylan1idotetrahydrothiophene (8) which upon treatment with a mixture of zinc, a lower aliphatic acid and a lower aliphatic acid anhydride, produces a mixture of 2- (4-carboXy-butylidene) -3 :4 di(acylamido)-tetrahydrothiophene ester (9a) and 2- (4-carboxybutyl) -3:4-di(acylamido) -4:5 -dihydrothiophene ester (92?) This mixture,"o11'fpreferred, one of the components, is then treated with hydrogen in the presence of a hydrogenation catalyst to yield stereoisomers of 2-(4'-carboxy-butyl) -'3 4-di- (acylamido) -tetrahydrothiophene ester (10). When this last mentioned compound is treated with an aqueous alkaline solution, hydrolysis of the acyl groups occurs, yielding upon acidification, 2-(4'-carboxybutyl) 3:4 diamino-tetrahydrothioplrene (11) which when reacted with a carbonyl halide, produces the compound 2-'(4'-carboxy-butyl) -3:4- ureido-tetrahydrothiophene. This product is obtained as a mixture of stereoisomers, one of which is racemic biotin, from which upon resolution, is obtained the dextrorotatory isomer, biotin.

invention is concerned generally with the class of compounds of which intermediate (8) above is a member, namely compounds of the class which consists of oximes, arylhydrozones and semicarbazones of 2-(omega-carboxyalkylidene) -3-keto-4-acylamido tetrahydrothiophenes and esters thereof, represented by the general formula:

drazin'e, and the like, semicarbazide, and salts thereof, with an ester of 2-(omega-carbo7ry-alkylidinL-B-ketoacylamido-tetrahydrothiophene. Corresponding acids are obtained-by hydrdlysis of the esters thus produced. The compounds used as starting materials are obtained by Tthe :process outlined above and described in detail in cc-pending applications, Serial Nos. 554,458; 554,449 now Patent 2,437,719; 554;450; 554.;451; 554.452 all filed Sept. 16, 1944. When a compound of the class which consists of hydroxylamine, arylhydrazines and semicarbazide orasaltthereof, is reacted'with an ester 'o'f'i2- About 2.3 g. of 2-(4-carbomethoxy-propylidene) -3-keto4-benzamido -tetrahydrothiophene are'added to .a solution-of approximately 0.75 g. of hydroxylamine hydrochloridein 15 cc. of pyridine, and, after-standing about 16 hoursat room temperature, the mixture is diluted with about 4 volumes of water and extracted with chloroform. The chloroform extract is cooled, washed at below 10 C. with hydrochloric acid (1 N), then with water, and dried. Upon evaporation of the chloroform the product, 2-(4'-carbomethoxypropylidene) -3-isonitroso-4- benzamido-tetrahydrothiophene is-obtained as an oil which is purified'byrecrystallization from methanol and ether to obtain the pure product (M. P. 16646? C).

'About 13.32 g. of 2-(4-carbomethoxy-butylidene) 3 keto-4benzamido tetrahydrothiophene and about 2.80 g. of hydroxylamine hydrochloride are dissolved in alcohol and mixed with about 50 cc. of dry pyridine. The mixture is allowed to stand about 15 hours at 30 C.,then it is diluted with four volumes of water and extracted with chloroform. The chloroform extract is cooled, shaken with hydrochloric acid (2.5 N), washed by shaking with water, dried and concentrated-at 40 C. Upon evaporation of the solvent a mass is obtained which is extracted with ether to remove impurities, and dried. The crude 2-(4'-carbomethoXy-butylidene) -3-isonitroso-4-benzylamido-tetrahydrothiophene thus obtained (M. P. 129-138 C.) is purified by repeated recrystallization from methanoL'yilding the pure oxime (M. P. 159-160 0.). When :the pure oxime is treated with alcoholicsodium hydroxide, then with aqueous acid, 2-(4-carboxybutylidene)-3-isonitroso-4 benzamido-tetrahydrothiophene (M. P. 203-204" C.) is obtained.

About 1.1 gms. of 2-(4-carbomethoxy-butylidene) -3-keto-4-benzamido-tetrahydrothiophene and about 0.5 g. of p-nitro-phenylhydrazine are added to approximately cc. methanol containing 2 drops of concentrated hydrochloric acid and the mixture refluxed until the p-nitrophenylhydrazine is completely dissolved. Upon cooling, the product crystallizes and is recrystallized from methanol to produce pure 2-(4'-carbomethoxybutylidene) -3- (p-nitrophenylhydrazino) -4-benzamido-tetrahydrothiophene; M. P. 154156 C.

idene) -3-keto-4-benzamido-tetrahydrothiophene and about 0.5 g. of 2:4-dinitrophenylhydrazine are added to approximately 10 cc. methanol containing 2 drops of concentrated hydrochloric acid and the mixture refluxed until the 2:4-dinitrophenylhydrazine is completely dissolved. Upon cooling, the product crystallizes and is recrystallized from methanol to produce pure 2-(4='-carbomethoxy butylidene) 3 (2:4 dinitrophenylhydrazino) -4-benzamido tetrahydrothiophene; M. P. 181-185" C.

It will be understood by persons versed in this field of invention that the above-described reactions can be conducted using as a starting material a compound within the general class of the 2 (omega carboxy alkylidene) -3-keto-4- acylamido-tetrahydrothiophene esters but having an acylamido group for example acetamido starting materials yi ld different from benzamido,

corresponding acetamido products, propamido starting materials yield propamido products, etc. The ester group, not being involved in or affected by the reaction, can be any alkyl, aryl or arylalkyl ester and a corresponding product is obtained, viz., propyl ester starting material yields propyl ester product, benzyl ester starting material yields benzyl ester product, etc.

Modifications may be made in carrying out the present invention without departing from the spirit and scope thereof and the invention is to be limited only by the appended claims.

We claim:

1. A compound selected from the group which consists of oximes, arylhydrazones and semicarbazones of 2-(omega-carboxy-alkylidene) -3- keto 4 acylainido tetrahydrothiophene, and alkyl, aryl, and arylalkyl esters thereof.

2. 2-(4'-carbomethoxy butylidene) -3-p-nitrophenylhydrazino) -4-benzamido tetrahydrothiophene.

3. 2-(4-carbomethoxy butylidene)-3-(2:4-dinitrophenylhydrazino) -4-benzamido-tetrahydrothiophene.

4. 2- (omega-carboxyalkylidene) -3-isonitroso- 4-acylamido-tetrahydrothiophene.

5. 2-(4-carboXy-butylidene) 3 benzamido-tetrahydrothiophene.

6. The process which comprises reacting a substance selected from the class consisting of hydroxylamine, arylhydrazines, and semicarbazides, and salts thereof, with a compound selected from the class which consists of alkyl, aryl and arylalkyl esters of 2-(omega-carboxy-alkylidene)-3- ketol-acylamido tetrahydrothiophene to produce the corresponding 3-nitrogen substitution product of said ketone.

7. Alkyl esters of 2-(4-carboxy-butylidene) -3- arylhydrazino-4-acylamido-tetrahydrothiophene.

8. The stereoisomer of 2-(4-carboXy-butylidene) -3-isonitroso-4-benzamido-tetrahydrothiophene having, when in substantially pure form, a melting point of 204 C.

9. The process which comprises reacting an arylhydrazine with an alkyl ester of 2-(4'- carboxy-butylidene) -3-keto-4-acylamido tetrahydrothiophene to produce the corresponding 3-arylhydrazino compound.

10. The process which comprises reacting hydroxylamine with an aryl ester of 2-(4'-carboxybutylidene) -3-keto-4-acylamido tetrahydrothiophene to produce the corresponding B-isonitroso compound.

11. The process which comprises reacting hydroxylamine with an arylalkyl ester of 2-(4'- carboxy-butylidene) -3-ket0-4-acy1amido tetrahydrothiophene to produce the corresponding 3-isonitroso compound.

12. The process which comprises reacting pnitrophenylhydrazine with 2-(4'-carbomethoxybutylidene) -3-keto-4 -benzamido-tetrahydrothiophene to produce the corresponding 3-(p-nitrophenylhydrazino) -compound.

13. The process which comprises reacting 2,4- dinitro-phenylhydrazine with 2-(4-carbomethoxy-butylidene) -3-keto 4 benzamido-tetrahydrothiophene to produce the corresponding 3- (2,4-dinitro-phenylhydrazino) -compound.

STANTON A. HARRIS. KARL FOLKERS.

REFERENCES CITED The following references are of record in the file oithis patent:

Karrer: Helv. Chim. Acta, 27, 132, 133, 144 (1944).

- isonitroso-e- 

